Broaching tool



Patented Feb. 6, 1934 `l Y .I

Bernard P. Schiltz, Cleveland, Chio, assigner to The Foote Burt Company, Cleveland, Ohio, a corporation of Ohio J l Application January 26, 1932. Serial No. 588,856

2 Claims. (Cl. S30- 33) This invention is directed to improvements in In the drawing I show one form of my invenmetal cutting tools and particularly to broaching tion, comprising a tool holder 10, suitably slotted tools, and the general object thereof is the proto firmly support a cutting tool l2, and the cutvision of a broaching tool having a multiplicity ting tool is secured to the holder in any approof cutting teeth, each having an interrelated rake priate manner, such as screw members 13. Any 60 and ute formation directed to the prevention number of the cutting tool blocks 12 may be utiof the sticking or clogging of the flutes with lized, as desired. InFig.l,atleast3of the blocks chips cut from the work by the teeth. 12 are illustrated. This tool holder may be uti- Other objects of my invention will become aplized in a breaching machine of the type wherein` w parent from the description hereinafter set forth, the tool is stationary and the work moves past 65 and which pertains to the accompanying drawthe tool or Vice versa as the tool is reciprocated ing. and the work held stationary.

In the drawing Fig. 1 is a side view of a broach In the particular illustration the teeth 14 are tool and a holder therefor, embodying the feaground to have a cutting rise of about two and tures of my invention; Fig. 2 is a cross section one-half thousandths inch per tooth, whereby 70 taken through the breach holder and tool and progressive cuts on the work are taken, as illussubstantially along the line 2-2 of Fig. 1; Fig. 3 trated in Fig. 4, where the work is indicated vby is an enlarged fragmentary view along the line W, and the teeth have the cutting edges thereof 3-3 of Fig. 2; Fig. 4 is an enlarged fragmentary extending normal to the side surfaces of the tool, side view illustrating the action of the cutting although there are other instances where the cut- 7 teeth upon a piece of work, while Fig. 5 is a frag- 4ting edges of the teeth would extend in relative mentary perspective of two of the multiplicity parallel relation but at an angle to the side faces of teeth, comprising the face of the tool. 15 of the tool. It will be obvious to those skilled Recent developments in the machine tool art in the art that the cutting rise per tooth is varied have brought into use so-called breaching maaccording to the metallurgical characteristics of S0 chines adapted to the machining of open face the metal comprising the work. work, as distinguished from prior well known In the instant tool structure, the rake angle broaching machines, which were adapted to finish R is about 121A?o and the face 16 is formed to terinternal surfaces of holes formed in the work. minate in an arc K (see Fig. 3), which is of a 3'0 This new type Of broaching machine has been lesser radius than the normal expanded radius 85 adapted to machining Operations heretofore efof the chip Wc when the chip euri breaks oir, and fected by milling and planing machines. I interrupt the arc formation 17 by forming a In COHYIECOH With this 116W type 0f mahine, groove 18 of greater depth than the extension of breaching tools are utilized which comprise a the rake face 16 and arc 17, whereby the chip as series of Cutting teeth formed in a substantially it curls becomes suspended out of contact with go COmmOII plane in the faces 0f blOCkS 0f JC001 Steel, the lowermost surface of the flute formation and the biOCkS preferably being mOUIlied UDDI! a i001 the flute width is made greater than the normal holder. The relatively high cutting Speeds at ,expanded diameter ofthe curled chip. The tooth which Such J60015 Carl be Passed OVBI the face 0f pitch or spacing of the teeth of the tool is also the Work t0 be finished, 0T Vice Versa, the Speeds such that a substantial body is provided to afford 95 of the work as it passes along the tool teeth are strength to each of the teeth 14.

such that problems of cutting lubrication and The arrangement of the groove 13 decreases Chip diSDOSal practically determine the rate 0f the contacting surface of the flute with the chips, production of said machine toolsthe degree of friction is reduced and the flute for- Y4.5 I have found that by predetermining the rake mation is such that when the curl breaks away 10o Of each Cutting 500i/if1 0f the 13001 t0 Obtain best from the work and expands, it cannot bind itself results in cutting speed and accuracy of nished in the u The Chips thus have no tendency surface and by modifying the usual flute formato become 'lodged in and 010g the gute,

tion relative to the rake angle and by departing From the foregoing it will be apparent that by' 5g from th'e usual flute CuIVatuI'eS that I Can Obtain reason'of the provision of the flute formation 105 disposition of the chips in a satisfactory manner Shown, the chips have ample opportunity to break without interfering in any Way with the proper and be washed out of the utes by the cutting application of the cutting lubricant orcompound compound or cutting lubricant. y

to the work as the same is being cut by the tool- 1 Claim;

teeth. A 1. A metal cutting tool having a plurality of 110 n parallel cutting teeth with flutes formed therebemames tween, the forward face of each tooth comprising a rake surface terminating in a flute arc, the rear surface of the preceding tooth being cut away at the base of the tooth to form a groove `which extends to a greater depth into the tool than the ute arc, and wherein said groove forms a surface on the rear face ofthe preceding tooth which is not intersected by said flute arc extended of the following tooth whereby chips cut by the tool are maintained at all times out of contact with the rear surface of the preceding tooth.

BERNARD P. SCHILTZ.

lac 

